The field of the invention is surfactants and the present invention relates to foam controlling additives useful therein.
The state of the art of surfactants may be ascertained by reference to the Kirk-Othmer "Encyclopedia of Chemical Technology", 2nd Edition, Vol. 19 (1969), pp. 507-593 under the section "Surfactants", British Patent Nos. 808,945 and 802,302; German Published Patent Application Nos. 1,080,250; 2,015,435 and 2,043,087 and German Patent Nos. 1,056,316 and 1,257,338, the disclosures of which are incorporated herein.
Foam controlling or antifoaming additives are required in washing and cleaning agents for washing machines and automatic dishwashers to prevent excessive foam development and particularly to prevent the washing liquid from frothing over. There is a strong foaming tendency especially in those washing and cleaning agents containing active wash components of the sulfate or sulfonate type. These are precisely the active wash substances ordinarily used.
Not only is it important to avoid frothing over in the machines and hence a loss of washing agents as regards the problem of foam control of washing agents, but also large amounts of foam are undesirable because they interfere with the mechanical manipulation of the material to be cleaned, so that the washing and cleaning agents in the machines do not achieve their full cleaning potential.
It is furthermore desirable that besides effectively attenuating the foaming of a washing agent within a given temperature range, there also is a balanced foaming behavior over all of the range.
Washing agents are already known, which contain soap mixtures acting as foam regulators as disclosed in German Published Patent Application Nos. 1,080,250 and 2,015,435, and British Patent Nos. 802,302 and 808,945, and German Patent No. 1,056,316 and Chemical Abstracts, Vol. 74, page 238 35 T. Soaps indeed are good foam inhibitors but however their application also entails drawbacks, namely the washing liquid is always alkaline and moreover they tend to form lime soaps.
Furthermore, washing agents are already known which contain for instance such diamides as N,N'-distearoylethylenediamine, as disclosed in German Published Patent Application No. 2,043,087 and reported in Chemical Abstracts, Vol. 77, page 22020 Y, or melamine derivatives such as 2,4,6-tridodecylamino-s-triazine as disclosed in German Patent No. 1,257,338, as antifoaming agents. While these formulations form approximately no foam at the higher temperatures, foam formation is excessive at the middle and lower ones, so that there is no balanced foaming behaviour throughout the entire temperature range.